Selective call communication systems that utilize battery saving techniques for extending battery life in selective call receivers operating therein are well known in the communications art. One such technique requires a system to queue pages in a plurality of queuing groups assigned to receivers in a predetermined manner for transmission at predetermined times. A selective call receiver operating on the system synchronizes with the transmissions from the system in a manner that allows the receiver to remain in a low-power stand-by mode until a predetermined transmission time assigned for the receiver's queuing group is imminent. Then the receiver briefly switches to a high-power receive mode to monitor the transmission of the assigned queuing group to determine whether there are any messages addressed to the receiver, after which the receiver returns to the low-power mode to conserve battery power.
A well-known improvement to the technique of grouping transmissions for battery saving comprises transmitting each queuing group of selective call addresses in a predetermined order, e.g., ascending order. This technique can allow the receivers, on average, to return to the low-power mode substantially halfway through the transmission of the queuing group. This is because each of the receivers can return to the low-power mode as soon as the receiver decodes an address higher than its own address without having received its own address.
Unfortunately, transmitting each group of selective call addresses in a predetermined order does not treat all receivers equally. A receiver having a low address near the start of the predetermined transmission order for the group consistently will be able to return to the low-power mode shortly after the start of the transmission of the queuing group. A receiver having a high address near the end of the predetermined transmission order for the group consistently will have to remain in the high-power mode for most or all of the transmission of the queuing group.
As a result of the address-dependent variable duration of the high-power mode, there is an imbalance in the effective amount of battery saving experienced, the low-address pager benefiting greatly from the ordering technique described above, while the high-addressed pager benefits little or not at all. This imbalance manifests itself in an imbalance in battery life, the low-addressed pager within the queuing group exhibiting a longer battery life than the high-addressed pager within the queuing group. In an idealized system all receivers would exhibit substantially equal battery life.
Thus, what is needed is a method and apparatus for equalizing battery life among battery-powered selective call receivers in a communication system utilizing periodic transmissions of queuing groups of selective call addresses queued into the queuing groups for battery saving, and further queued into transmission positions having a predetermined queuing order within the queuing groups. The method and apparatus preferably should achieve battery saving benefits comparable to those that would be achieved by consistently returning every receiver to the low-power mode substantially halfway through the transmission of the queuing group to which the receiver belongs.
An aspect of the present invention is a method of equalizing battery life among a plurality of battery-powered selective call receivers in a communication system utilizing periodic transmissions of selective call addresses queued into queuing groups for battery saving, and further queued into transmission positions having a predetermined queuing order within the queuing groups for additional battery saving. The method comprises the step of periodically changing, in a system controller, the predetermined queuing order. The changing step comprises the steps of queuing a first plurality of selective call addresses into a first plurality of queuing groups for a first transmission, wherein the first plurality of selective call addresses are queued in a first predetermined queuing order; and queuing a second plurality of selective call addresses into a second plurality of queuing groups for a second transmission, wherein the second plurality of selective call addresses are queued in a second predetermined queuing order substantially equal to the first predetermined queuing order in reverse. The changing step further comprises the step of alternately transmitting to the plurality of battery-powered selective call receivers the first plurality of queuing groups and a first queuing order indicator for identifying the first predetermined queuing order, followed by the second plurality of queuing groups and a second queuing order indicator for identifying the second predetermined queuing order. At least one of the plurality of battery-powered selective call receivers is pre-programmed with an individual selective call address comprising a queuing group indicator for indicating membership in a particular queuing group, and further is pre-programmed with information defining predetermined queuing orders utilized by the communication system. The method further comprises in a receiver of the at least one of the plurality of battery-powered selective call receivers the steps of receiving a queuing order indicator for indicating one of the predetermined queuing orders utilized for a corresponding transmission of a queuing group, and detecting that the initiation of a transmission of the particular queuing group matching the queuing group indicator pre-programmed into the receiver is imminent. The method also includes the step of controlling reception and decoding of the selective call addresses transmitted in the particular queuing group for a specific duration in response to the detecting step, wherein the specific duration is determined by examination of ones of the selective call addresses in accordance with the received queuing order indicator.
Another aspect of the present invention is an apparatus for equalizing battery life among a plurality of battery-powered selective call receivers in a communication system having a system controller utilizing periodic transmissions of selective call addresses queued into queuing groups for battery saving, and further queued into transmission positions having a predetermined queuing order within the queuing groups for additional battery saving. The apparatus comprises a rotation element in the system controller for periodically changing the predetermined queuing order. The rotation element comprises a first queuing element for queuing a first plurality of selective call addresses into a first plurality of queuing groups for a first transmission, wherein the first plurality of selective call addresses are queued in a first predetermined queuing order; and a second queuing element coupled to the first queuing element for queuing a second plurality of selective call addresses into a second plurality of queuing groups for a second transmission, wherein the second plurality of selective call addresses are queued in a second predetermined queuing order substantially equal to the first predetermined queuing order in reverse. The apparatus further comprises a transmitter coupled to the first and second queuing elements for alternately transmitting to the plurality of battery-powered selective call receivers the first plurality of queuing groups and a first queuing order indicator for identifying the first predetermined queuing order, followed by the second plurality of queuing groups and a second queuing order indicator for identifying the second predetermined queuing order. At least one of the plurality of battery-powered selective call receivers is pre-programmed with an individual selective call address comprising a queuing group indicator for indicating membership in a particular queuing group, and further is pre-programmed with information defining predetermined queuing orders utilized by the communication system. The apparatus further comprises in the at least one of the plurality of battery-powered selective call receivers a receiver element coupled by radio to the transmitter for receiving a queuing order indicator for indicating the predetermined queuing order utilized for a corresponding transmission of a queuing group, and a detector element coupled to the receiver element for detecting that the initiation of a transmission of the particular queuing group matching the queuing group indicator pre-programmed into the battery-powered selective call receiver is imminent. The apparatus further comprises in the at least one of the plurality of battery-powered selective call receivers a controller coupled to the detector element and to the receiver element for controlling reception and decoding of the selective call addresses transmitted in the particular queuing group for a specific duration in response to the initiation of the transmission being imminent, wherein the specific duration is determined by examination of ones of the selective call addresses in accordance with the received queuing order indicator.
Another aspect of the present invention is a system controller for equalizing battery life among a plurality of battery-powered selective call receivers in a communication system including a transmitter and utilizing periodic transmissions of selective call addresses queued into queuing groups for battery saving, and further queued into transmission positions having a predetermined queuing order within the queuing groups for additional battery saving. The system controller comprises a page input for receiving page requests from callers wishing to page one of the plurality of battery-powered selective call receivers, and a memory element coupled to the page input for storing the received page requests for subsequent transmission. The system controller further comprises a rotation element for periodically changing the predetermined queuing order. The rotation element comprises a first queuing element for queuing a first plurality of selective call addresses into a first plurality of queuing groups for a first transmission, wherein the first plurality of selective call addresses are queued in a first predetermined queuing order; and a second queuing element coupled to the first queuing element for queuing a second plurality of selective call addresses into a second plurality of queuing groups for a second transmission, wherein the second plurality of selective call addresses are queued in a second predetermined queuing order substantially equal to the first predetermined queuing order in reverse. The system controller further comprises an encoder/transmitter controller coupled to the first and second queuing elements and to the transmitter for controlling the transmitter to alternately transmit to the plurality of battery-powered selective call receivers the first plurality of queuing groups and a first queuing order indicator for identifying the first predetermined queuing order, followed by the second plurality of queuing groups and a second queuing order indicator for identifying the second predetermined queuing order.
Yet another aspect of the present invention is a battery-powered selective call receiver for equalizing battery life among a plurality of the battery-powered selective call receivers in a communication system utilizing periodic transmissions of selective call addresses from a transmitter, the selective call addresses queued into queuing groups for battery saving, and further queued into transmission positions having a predetermined queuing order within the queuing groups for additional battery saving. The battery-powered selective call receiver comprises a first memory element having pre-programmed therein an individual selective call address for identifying the battery-powered selective call receiver, and a queuing group indicator for indicating membership in a particular queuing group. The battery-powered selective call receiver further comprises a second memory element coupled to the first memory element and pre-programmed with information defining predetermined queuing orders utilized by the communication system, and a receiver element coupled to the transmitter for receiving a queuing order indicator for indicating the predetermined queuing order utilized for a corresponding transmission of a queuing group. The battery-powered selective call receiver also includes a detector element coupled to the receiver element and to the first memory element for detecting that the initiation of a transmission of a particular queuing group matching the queuing group indicator pre-programmed into the first memory element is imminent; and a controller coupled to the detector element and to the receiver element for controlling reception and decoding of the selective call addresses transmitted in the particular queuing group for a specific duration in response to the initiation of the transmission being imminent. The specific duration is determined by examination of ones of the selective call addresses in accordance with the received queuing order indicator.
Still another aspect of the present invention is a system controller for equalizing battery life among a plurality of battery-powered selective call receivers in a communication system including a transmitter and utilizing periodic transmissions of selective call addresses queued into queuing groups for battery saving, and further queued into transmission positions having a predetermined queuing order within the queuing groups for additional battery saving. The system controller comprises a page input for receiving page requests from callers wishing to page one of the plurality of battery-powered selective call receivers, and a memory element coupled to the page input for storing the received page requests for subsequent transmission. The system controller further comprises a rotation element for periodically changing the predetermined queuing order such that each of the selective call addresses experiences a queuing delay between an initiation of a transmission of a queuing group and a transmission of the selective call address queued in the queuing group. The queuing delay averaged over a plurality of queuing group transmissions approaches a single, constant value substantially applicable to each of the selective call addresses. The rotation element comprises a starter element for designating a rotating starting point for the predetermined queuing order, from which the selective call addresses are queued in a predetermined order until all the selective call addresses have been queued.